Polymer dynamics thrrough fix langevin/fix nve

Hello all,
The polymer system is equilibrating well with fix nve.With fix langevin and fix nve thr program is running without any error, but even after the run is complete the system is stiff, hardly displaced from equilibrated position.Is there any other requirements we are supposed to fulfill with fix langevin command.
Any advice or help would be greatly appreciated.
Thankyou
Andri

#lammps command

variable r equal floor(random(90,9850658,900))
units real
boundary f f f
atom_style full
bond_style fene
pair_style lj/cut 1.12246204831
read_data data1.polymer
bond_coeff 1 15.0 2.0 1.0 1.0
special_bonds lj 0.0 1.0 1.0

pair_modify shift yes
pair_coeff 1 1 1.0 1.0 1.12246
pair_coeff 2 2 1.0 1.0 1.12246
pair_coeff 1 2 1.0 1.0 1.12246

Only the groupB(wall) atoms are immobile.

#group mobile molecule <> 92 219
group groupB molecule <> 1 90
group mobile subtract all groupB
group polyA molecule <> 92 218

print “--------- beginning equilibration ---------”

velocity groupB set 0.0 0.0 0.0
fix 2 groupB setforce 0.0 0.0 0.0

timestep 0.5
group one id 219
velocity one set 0.0 0.0 0.0
fix 10 one setforce 0.0 0.0 0.0
velocity polyA create 1.2 $r
velocity polyA set NULL NULL 0.0
#fix fxlan mobile langevin 1.2 1.2 1.5 $r
fix fxnve polyA nve
run 500
reset_timestep 0
unfix 10

#Run

fix freeze groupB rigid single force * off off off torque * off off off
fix 4 mobile setforce NULL NULL 0.0
region 20 block -0.5 0.5 -0.5 0.5 0.0 0.0
fix 6 mobile addforce 5.0 0.0 0.0 region 20
#velocity mobile create 1.2 $r
velocity mobile set NULL NULL 0.0
fix fxlan mobile langevin 1.2 1.2 1.5 $r
fix fxnve mobile nve
timestep 0.1
dump 1 all custom 1000 new.lammpstrj id mol type x y z ix iy iz
run 300000

unfix 4
unfix freeze
unfix 6
reset_timestep 0
clear

you are using real units, but most of your parameters are in the
numeric range typically used for reduced units (except those related
to time).
thus, for example, your particles are smaller than usual by a factor
of 3-5, while your interaction energies are orders of magnitude
stronger, while you are simulating at temperatures close to 0K.

so it is not surprising at all, that your system doesn't move much.

axel.